Three out of four Americans believe children should be vaccinated against measles even if their parents object, a Reuters/Ipsos poll found, showing little sympathy for the anti-vaccination movement that U.S. officials blame for the ongoing outbreak.

Some 764 cases of the disease have been confirmed in the United States so far this year, the most seen in 25 years, in an outbreak that public health officials have called "completely avoidable" and largely linked to misinformation campaigns against the vaccines.

A small but vocal community of parents refuse to vaccinate their children, citing concerns about the injections that are not supported by science. But the Reuters/Ipsos poll showed U.S. adults by a wide majority share the scientific consensus that the highly contagious and sometimes deadly disease is dangerous, while vaccines are safe.

Eighty-five percent of the 2,008 adults polled April 30 through May 2 said that all children should be required to get vaccinated unless there was a medical reason not to, such as an allergy or compromised immune system. Some 77 percent said children should be immunized even if their parents object to the vaccinations.

"Those numbers are not really as high as they should be," said Dr. Jennifer Lighter, an epidemiologist at NYU Langone Health hospital in New York. "It's putting children at risk and other people at risk who are vulnerable to severe measles if you're not vaccinating your own child."

In order to achieve herd immunity that protects those unable to get the measles vaccine, such as infants and people with compromised immune systems, 90% to 95% of the population needs to be vaccinated.

Less than 4 percent of respondents said they do not believe the vaccine is safe.

State and local officials in recent weeks have looked at new ways to fight the outbreak. In New York City, where some 423 cases have been recorded, Mayor Bill de Blasio last month issued a mandatory vaccination order for Brooklyn's Williamsburg neighborhood and other communities hard-hit by the disease.

Lawmakers in a half-dozen states are mulling new measures that would prohibit parents from citing religious or personal beliefs to avoid vaccinating their children.

"The government's role should definitely be to mandate the vaccine," Lighter said. "It is a safety issue. It's a law to wear your seatbelt, it should be a law to get vaccinated."

Officials have also warned that certain adults living in areas hard-hit by the epidemic, which include parts of California, New Jersey and Michigan, may need another shot to ensure that they are protected from measles.

Many adults are unsure if they remain immune, given that vaccinations are typically administered early in childhood. Twenty-two percent of respondents told Reuters/Ipsos that they either are not vaccinated for the disease or don't remember if they are.

Doctors attributed this memory failure to the fact that many people got the vaccine as young children and often do not have documentation because they received it before electronic records were kept.

"That's one of the most crucial areas where we can intervene," said Dr. Teresa Dean, an internist at Cedars-Sinai Medical Center in Los Angeles. Doctors recommend that adults who are unsure of their immunity should get tested and then get the vaccine if needed.

The poll has a credibility interval, a measure of accuracy, of 3 percentage points.